Stop Blaming Food Poisoning On The Last Thing You Ate

Stop Blaming Food Poisoning On The Last Thing You Ate
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You’re on your hands and knees praying to the porcelain god, and between each of your wretched retches you curse the name of that restaurant you ate at a few hours earlier. But that place is probably not the culprit, even if you’re seeing that meal in reverse.

Painting by Roy Blumenthal.

When you get so-called “food poisoning” it’s almost never the last thing you ingested. As Dr Deborah Fisher, a gastroenterologist and professor at Duke University, explains to the New York Times, the cause is probably the thing before the last thing you ate. That means, if you get sick at night, your dinner isn’t to blame, it’s your lunch. But why is that?

For starters, food takes a while to break down inside your body. On average, it takes your stomach at least four to six hours to work through a meal, plus six to eight hours in the small intestine. It’s unlikely you’ll start to get sick until this process is in full swing. That said, everybody’s “bowel transit time” varies. If you’re not sure what yours is, gastroenterologists suggest you can find out with what’s known as the “corn test”. Basically, you eat some corn, then watch for the indigestible kernels to show up in your stool. You might be surprised how long it takes.

More importantly, however, is the fact that “food poisoning” is usually caused by a typical stomach bug. Thing is, these bugs require an incubation period before you show any symptoms. The most common stomach bugs such as Norovirus, Campylobacter and E. coli takes at least a day to kick in — sometimes several days. Costridium perfringens, Vibrio parahaemolyticus and Salmonella are the quickest to the draw, but they still have incubation periods long enough to make it unlikely your sickness came from the previous meal. The FDA has a handy chart to explain them all.

Also, food isn’t always to blame for vomiting and diarrhoea. Even if you’ve picked up one of the stomach bugs mentioned above, there’s no way to know where it actually came from. Maybe you forgot to wash your hands after touching something covered in germs, like your phone or a railing, then ate some finger food. Or perhaps your late-night heaving isn’t caused by anything you ingested at all. Stress, anxiety, anger, sadness and other taxing things that weigh on your mind could be what’s causing the problem. So, before you get angry and blame that ethnic restaurant, think about your food poisoning timeline.


  • This goes completely against what doctors have told me in the past. Pretty sure the last one said 3-6 hours from eating. So if you’re sick at 10pm it’s more likely dinner than lunch *unless* you’ve been feeling nauseous for several hours. Of course the doc could be wrong.

    Another cause for what we put down as stomach bugs is food allergies. I’ve discovered I’m allergic to the orange food colouring used in Fanta. Same symptoms as food poisoning just super rapid onset – like without half an hour. So keep food allergies in mind too, even foods you’ve previously eaten ok could provoke an allergic reaction 🙁

  • How is “bowel transit time” a factor? If you’re sick, everything inside you is aiming to get out ASAP – the reason diarrhoea is watery is because it hasn’t spent long enough in the intestines for the water to be absorbed.

    Also, a lot of food poisoning is caused by toxins produced by bacteria, not by the bacteria themselves, many of which would not survive the acidic environment of your stomach. If you eat a piece of cheesecake that’s been out of the fridge for 4 hours, that’s 4 hours during which the bacteria on it have been working hard to produce a lovely load of toxins, which are going to affect you pretty soon after you ingest them.

  • I don’t think bowel transit time itself is the issue, more that if you eat something and feel sick almost immediately that food has probably not had time to be digested enough to cause an issue

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